Underreading errors, false-negative interpretations, are the most frequent and costly type of error occurring in diagnostic radiology. A subset of these underreading errors have been attributed to "satisfaction of search" which occurs when a second lesion remains undetected following the detection of an initial lesion in a radiograph (Tuddenham, 1961, 1963; Smith, 1967). Our previous endeavors supported by an NIH award were the first to study satisfaction of search (SOS) in the experimental laboratory (using an appropriate control condition). Our overall purpose in studying satisfaction of search is to gain understanding of this and other types of error necessary to reduce their frequency. The first experiment showed reduced detection accuracy of inherent lesions in chest radiographs after the addition of artificial nodules rigorously demonstrating the existence of SOS and establishing a paradigm to study the phenomenon. In a second experiment just completed, inspection times before responses and termination of search were measured to determine whether SOS is caused by premature termination of search or perceptual capture. These preliminary studies provide a framework in which definitive research can address the complex questions that remain. The first two proposed experiments attempt to confirm and extend our finding to other types of images and abnormalities. In the first experiment, multiple fractures appearing in a series of radiographs will be used to determine whether SOS can extend across a series of radiographs of an individual when both distractor and target abnormalities are of the same nature. The second experiment will also mimic a condition known to be error prone in gastrointestinal contrast studies. The purpose is to determine whether other aspects of images besides the initial detection of a lesion can influence visual attention to create SOS. The target abnormalities will be demonstrable without contrast, the contrast material will serve as the distractor. A third experiment tests the interaction of clinical history and satisfaction of search to resolve a controversy in the literature regarding the influence of clinical history upon radiographic detection. Lack of agreement in the findings of numerous studies may be explained by whether single or multiple abnormalities were included in each image. Satisfaction of search, which occurs with multiple abnormalities, might cancel the improvement that might be afforded for abnormalities suggested by clinical history were only one abnormality present on a radiograph.